ON  A  CONVENIENT  PROCESS  FOR  PREPARING  OXYGEN.  373 
ON  A  CONVENIENT  PROCESS  FOR  PREPARING  OXYGEN. 
By  M.  Fleitman. 
The  easy  preparation  of  oxygen  for  technical  purposes  is  a  mat- 
ter of  considerable  importance,  and  I  now  shortly  describe  a  pro- 
cess which  possesses  particular  scientific  interest.  I  was  led  to 
the  process  by  observing  that  on  heating  a  concentrated  solution 
of  chloride  of  lime  with  only  a  trace  of  freshly  prepared  moist 
peroxide  of  cobalt,  *  the  hypochlorite  of  lime  was  completely  de- 
composed into  chloride  of  calcium  and  oxygen.  Repeated  quan- 
titative experiments,  the  results  of  which  I  have  lost,  convinced 
me  that  the  whole  of  the  oxygen  was  evolved,  and  that  only  chlo- 
ride of  calcium  and  no  chloric  acid  was  formed. 
The  evolution  of  oxygen  commences  about  70°  or  80°, 
and  continues  in  a  regular  stream,  with  a  slight  frothing  of  the 
liquid. 
The  action  of  the  peroxide  of  cobalt  in  this  case,  it  is  clear, 
is  exactly  like  that  of  nitric  oxide  in  the  manufacture  of  sulphuric 
acid.  There  is  no  doubt  that  several  peroxides  of  cobalt  with 
various  proportions  of  oxygen  exist.  My  own  experiments  have 
shown  me  that  the  proportion  of  oxygen  in  peroxide  of  cobalt  is 
variable,  and  the  simplest  explanation  of  this  process  is  that  a 
lower  peroxide  abstracts  oxygen  from  the  hypochlorite  of  lime  to 
form  a  higher  oxide,  which  is  again  decomposed  into  a  lower  oxide 
and  oxygen. 
The  peroxide  made  use  of  in  one  experiment  may  be  employed 
again  to  decompose  a  fresh  quantity  of  hypochlorite  of  lime. 
From  one-tenth  to  one-half  per  cent,  is  sufficient  to  effect  the  re- 
action ;  and  instead  of  taking  the  freshly  prepared  hydrated  per- 
oxide, it  will  suffice  to  add  to  the  solution  of  hypochlorite  a  few 
drops  of  a  solution  of  cobalt  salt,  whereby  a  corresponding  amount 
of  the  peroxide  is  formed. 
The  advantages  of  this  method  of  procuring  oxygen  appear  to 
be  the  following  : — 
1.  The  evolution  proceeds  with  extraordinary  regularity,  and 
the  gas  is  collected  with  the  greatest  ease,  which  makes  the  pro- 
*  Peroxide  of  nickle  acts  in  a  similar  way,  but  not  so  energetically. 
